1. Field of the Invention
This invention pertains to the art of collet chucks and more particularly to an improved collet chuck useful in the fabrication of gas risers such as are used in the transmission of natural gas into residential homes.
2. Description of the Related Art
Mechanisms for gripping tubular workpieces by moving segmented gripping surfaces radially inwardly or outwardly are known in the art. Most of these mechanisms grip the workpiece through discrete points of contact about the periphery of the workpiece such as U.S. Pat. No. 4,366,732 to Schliep. Others endeavor to grip the workpiece with more than point contact, such as U.S. Pat. No. 2,407,083 to Koppel. Some have utilized ramps which move the gripping surfaces radially inwardly and outwardly such as U.S. Pat. No. 401,962 to McCanna and U.S. Pat. No. 2,893,292 to Hollis.
While these inventions have been generally useful in their fields, further advantages were desirable, especially in the area of increasing the effective gripping surface area of the collet chuck.
The present invention contemplates a new and improved collet which is simple in design, effective in use, and overcomes the foregoing difficulties and others while providing better and more advantageous overall results.